1. Field of the Invention
This invention relates to laminates of a substrate and polyether urethane foam, and particularly to such laminates that are produced by heat sealing. More particularly, the invention relates to urethane foam laminates wherein the urethane foam is treated with a phosphorus-containing additive.
2. Related Information
In the preparation of many articles which employ flexible polyurethane foams, it is necessary to form an adhesive bond between the foam and a substrate such as wood, a fabric, a metal and organic plastic, etc. Heat sealing is a useful process for adhering a polyurethane foam to a substrate. In this process, the surface of a foam is heated to form a layer of tacky liquid, after which the substrate is applied to the fused surface of the foam to form a laminate. When the layer of tacky liquid cools and resolidifies, the resulting bond between the polyurethane foam and the substrate is frequently as strong or stronger than the strength of the original polyurethane foam. Heretofore, only polyester-type urethane foams were laminatable in this manner. The less expensive polyether-type urethane forms could not be heat sealed because the fused surface layer would not resolidify.
U.S. Pat. No. 3,205,120 [Flanders, Sept. 7, 1965] discloses heat sealed urethane foam laminates that are prepared from the less expensive polyether urethane foam. This patent discloses that in an otherwise conventional commercial polyether flexible urethane foam reaction mixture, a minor amount of a low molecular weight polyol selected from the group consisting of a polyoxyalkylene polyol, a hydroxyaliphatic ester of a phosphorus-containing acid and a hydroxyl-containing natural oil was included.
U.S. Pat. No. 3,497,416 [Critchfield et al., Feb. 24, 1970] discloses heat sealed urethane foam laminates prepared from polyether-based urethane foam. The urethane foam comprises the reaction product of a polyether polyol and polyisocyanate prepared by reacting dipropylene glycol or dibutylene glycol with an excess of an aromatic polyisocyanate. This patent identifies certain processing difficulties encountered in the production of polyether urethane foams as disclosed in Flanders that are caused by the high reactivity of the polyether polyol mixture used.
U.S. Pat. No. 3,131,105 [Codos, Apr. 28, 1964] discloses a method for forming a laminated structure by applying onto the surface of a polyurethane foam, a coating of an inflammable substance which when ignited will plasticize said surface, igniting said coating to plasticize the surface and then applying with pressure a layer of material with which the plasticized surface will form a bond onto the plasticized surface while the surface is soft and tacky. This method is useful for both polyesters and polyether urethane foams, however, it does not disclose the use of any additives within these foams.
U.S. Pat. No. 3,142,650 [Friedman, July 28, 1964] discloses the preparation of polyurethanes from phosphite esters containing available secondary hydroxyl groups, for example a tris-polypropylene glycol phosphite. This patent does not disclose heat sealable polyether urethane foam laminates.
U.S. Pat. No. 3,142,651 [Friedman, July 28, 1964] discloses the preparation of polyurethanes from phosphite esters containing available hyroxyl groups, preferably secondary hydroxyl groups. The patent also discloses the preparation of polyurethanes from the corresponding thiophosphate esters, phosphate esters and certain phosphonates. This patent does not disclose heat sealable polyether urethane foam laminates.
U.S. Pat. No. 4,135,042 [Lickei et al., Jan. 16, 1979] discloses the use of phosphites as scorch inhibitors in polyurethane foams containing halogenated phosphate polyester additives. Again this patent does not disclose heat sealable polyether urethane foam laminates.